An integrated system and method for efficient treatment and resource recycling of printing and dyeing wastewater

Abstract

This invention discloses an integrated system and method for the efficient treatment and resource reuse of dyeing and printing wastewater. The system includes an equalization tank, an aerobic granular sludge reactor, an aerated biological filter, an ultrafiltration unit, and a reverse osmosis unit, all connected by pipes along the wastewater flow direction. The aerobic granular sludge reactor serves as a highly efficient pretreatment system, rapidly removing most organic matter and nitrogen and phosphorus, reducing subsequent load. The aerated biological filter, as a deep biological treatment system, specializes in treating recalcitrant organic matter and decolorizing, providing high-quality feed water for the membrane system. The dual-membrane system, consisting of a polyvinylidene fluoride hollow fiber membrane in the ultrafiltration unit and a polyamide composite membrane in the reverse osmosis unit, ensures the quality of the final effluent. These three systems are connected in series, forming a gradient treatment mode of "biological enhancement + deep filtration + precision separation," synergistically enhancing the final effluent quality, which is clear and far superior to reuse water standards. This effluent can be directly reused in the rinsing and dyeing processes of dyeing and printing production, achieving a closed-loop water resource cycle.

Description

Technical Field

[0001] This invention relates to the field of dyeing and printing wastewater treatment technology, and more specifically, to an integrated system and method for efficient treatment and resource recycling of dyeing and printing wastewater. Background Technology

[0002] Dyeing and printing wastewater has a complex composition, containing large amounts of dyes, auxiliaries, and recalcitrant organic matter. It is characterized by high COD, high color, high salinity, and large fluctuations in water quality, making it a recognized difficult-to-treat industrial wastewater. Traditional anaerobic-aerobic biological treatment processes suffer from low load, poor decolorization, and insufficient nitrogen and phosphorus removal efficiency, making it difficult for effluent to consistently meet standards. Although the "dual-membrane method" (ultrafiltration UF + reverse osmosis RO) can be used for advanced treatment and reuse, directly treating the biological effluent from dyeing and printing wastewater greatly increases the risk of membrane fouling, leading to high operating costs and poor system stability.

[0003] While existing technologies utilize aerobic granular sludge (AGS) and aerated biological filters (BAF) individually for the pretreatment of dyeing and printing wastewater, they suffer from limitations such as single-function limitations and limited removal of recalcitrant organic matter and color. Currently, there is a lack of an integrated system that organically couples efficient biological pretreatment units with advanced membrane treatment units and comprehensively optimizes the treatment based on the specific characteristics of dyeing and printing wastewater, thereby achieving efficient, stable, low-cost treatment and resource reuse of the wastewater. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an integrated system and method for efficient treatment and resource reuse of dyeing and printing wastewater that is efficient, stable, economical and easy to manage. Through the optimized coupling and synergistic effect of aerobic granular sludge reactor, aerated biological filter and dual membrane process, the system achieves efficient removal of pollutants from dyeing and printing wastewater. The final product water quality can be directly reused in production, significantly reducing investment and operating costs.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An integrated system for the efficient treatment and resource reuse of dyeing and printing wastewater includes an equalization tank, an aerobic granular sludge reactor, an aerated biological filter, an ultrafiltration device, and a reverse osmosis device, all connected by pipelines along the wastewater flow direction. The equalization tank is used to equalize the water quality and quantity of the dyeing and printing wastewater. The aerobic granular sludge reactor is used for biodegradation and nitrogen and phosphorus removal treatment of the effluent from the equalization tank. The aerated biological filter is used for deep biological treatment and filtration of the effluent from the aerobic granular sludge reactor. The ultrafiltration device is used for physical sieving and colloidal removal of the effluent from the aerated biological filter. The reverse osmosis device is used for desalination and deep purification of the ultrafiltration permeate, and its permeate is connected to a reuse water tank. The system also includes a PLC automatic controller electrically connected to the aerobic granular sludge reactor, the aerated biological filter, the ultrafiltration device, and the reverse osmosis device. The PLC automatic controller dynamically adjusts the operating parameters of each unit to optimize the overall system efficiency and respond to fluctuations in the influent water quality.

[0007] Furthermore, the aerobic granular sludge reactor is a sequencing batch reactor (SBR).

[0008] Furthermore, the aerated biological filter is filled with granular biological packing material and uses continuous aeration.

[0009] Furthermore, the ultrafiltration device uses a polyvinylidene fluoride hollow fiber membrane and undergoes periodic backwashing.

[0010] Furthermore, the reverse osmosis device uses a polyamide composite membrane.

[0011] This invention also provides a method for the efficient treatment and resource reuse of dyeing and printing wastewater, comprising the following steps:

[0012] Step S1: The dyeing and printing wastewater enters the equalization tank for homogenization and equalization.

[0013] Step S2: The effluent from the equalization tank enters the aerobic granular sludge reactor for biological treatment to remove most of the organic matter and nitrogen and phosphorus pollutants.

[0014] Step S3: The effluent from the aerobic granular sludge reactor enters the aerated biological filter for deep treatment to remove recalcitrant organic matter and color.

[0015] Step S4: The effluent from the aerated biological filter is filtered by an ultrafiltration device to remove suspended solids and colloids.

[0016] In step S5, the ultrafiltration permeate enters the reverse osmosis unit for desalination and fine treatment to obtain permeate that meets the reuse standards.

[0017] Furthermore, the PLC automatic controller monitors the operating status and water quality parameters of each unit in the system in real time, and dynamically adjusts the operating cycle of the aerobic granular sludge reactor, the aeration rate of the aerated biological filter, the backwashing frequency of the ultrafiltration device, and the operating pressure of the reverse osmosis device.

[0018] The beneficial effects of this invention are:

[0019] 1. In this invention, the aerobic granular sludge reactor serves as a highly efficient pretreatment, rapidly removing most organic matter and nitrogen and phosphorus, thus reducing subsequent loads; the aerated biological filter, as a deep biological treatment, specializes in treating recalcitrant organic matter and decolorizing, providing high-quality feed water for the membrane system; the dual membranes, consisting of the polyvinylidene fluoride hollow fiber membrane of the ultrafiltration unit and the polyamide composite membrane of the reverse osmosis unit, ensure the final effluent quality; the three are connected in series to form a gradient treatment mode of "biological enhancement + deep filtration + precision separation," synergistically enhancing the effect, resulting in clear effluent quality far exceeding the standards for reused water, which can be directly reused in the rinsing, dyeing, and other processes of printing and dyeing production, realizing a closed-loop cycle of water resources, with significant environmental and economic benefits.

[0020] 2. In this invention, the aerobic granular sludge has a compact structure and is rich in microorganisms, while the biofilm in the aerated biological filter adheres and grows. The combination of the two gives the system a strong buffering capacity against fluctuations in the water quality and quantity of dyeing and printing wastewater, and strong resistance to shock loads. At the same time, through the deep pretreatment of the aerobic granular sludge reactor and the aerated biological filter, colloids, suspended solids and macromolecular organic matter that are prone to causing membrane fouling are effectively removed, which greatly reduces the fouling load of polyvinylidene fluoride hollow fiber membranes and polyamide composite membranes, extends the membrane cleaning cycle and service life, and reduces the frequency of chemical cleaning and energy consumption.

[0021] 3. This invention achieves fully automated control of the entire process through a PLC automatic controller, which simplifies operation and management, reduces manual intervention, and ensures long-term stable operation of the system. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of an integrated system for efficient treatment and resource recycling of dyeing and printing wastewater in this embodiment.

[0023] Figure labels: 1. Equalization tank; 2. Aerobic granular sludge reactor; 3. Aerated biological filter; 4. Ultrafiltration device; 5. Reverse osmosis device; 6. PLC automatic controller. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] An integrated system for the efficient treatment and resource reuse of dyeing and printing wastewater, such as Figure 1 As shown, the system includes an equalization tank 1, an aerobic granular sludge reactor 2, an aerated biological filter 3, an ultrafiltration device 4, and a reverse osmosis device 5, all connected by pipes along the wastewater flow direction. Through the optimized coupling and synergistic effect of the aerobic granular sludge reactor 2, the aerated biological filter 3, and the dual-membrane process, the system achieves efficient removal of pollutants from dyeing and printing wastewater. The final product water quality is superior to the recycled water quality standards of the textile dyeing and finishing industry and can be directly reused in production, while significantly reducing investment and operating costs.

[0026] The equalization tank 1 is used to equalize the water quality and quantity of dyeing and printing wastewater; the aerobic granular sludge reactor 2 is used for biodegradation and denitrification and phosphorus removal of the effluent from the equalization tank 1; the aerated biological filter 3 is used for deep biological treatment and filtration of the effluent from the aerobic granular sludge reactor 2; the ultrafiltration device 4 is used for physical screening and removal of colloidal substances from the effluent from the aerated biological filter 3; and the reverse osmosis device 5 is used for desalination and deep purification of the ultrafiltration permeate, and its permeate is connected to the recycled water tank.

[0027] Specifically, the aerobic granular sludge reactor 2 is a sequencing batch reactor (SBR), and its operating parameters are controlled as follows: organic loading rate (OLR) of 2.0~4.0 kg / (m³). 3 ·d), preferably 3.0 kg / (m 3 •d); Dissolved oxygen (DO) is 2~4 mg / L; sludge concentration (MLSS) is 8000~10000 mg / L; the operating cycle is 6~8 cycles / day, each cycle includes influent, aeration, sedimentation, drainage and idle phases.

[0028] The aerated biological filter 3 is filled with granular biological packing material, with a filling ratio of 70%~80%. Its operating parameters are controlled as follows: hydraulic retention time (HRT) of 2~4 hours; dissolved oxygen (DO) of 4~5 mg / L; and continuous aeration mode.

[0029] Ultrafiltration unit 4 uses a polyvinylidene fluoride (PVDF) hollow fiber membrane, and its operating parameters are controlled as follows: membrane flux is 20~30 L / (m²). 2 ·h), preferably 25L / (m 2•h); Operating pressure is 0.1~0.3MPa; Operating mode is dead-end filtration combined with periodic backwashing, with a backwashing cycle of 30min and a backwashing time of 30s.

[0030] The reverse osmosis unit 5 uses a polyamide composite membrane, and its operating parameters are controlled as follows: operating pressure is 1.0~1.5MPa, preferably 1.2MPa; the designed recovery rate is 60%~70%; and the pH value of the system feed water is controlled at 6.5~7.5.

[0031] In the aforementioned system, the aerobic granular sludge reactor 2 serves as a highly efficient pretreatment, rapidly removing most organic matter and nitrogen and phosphorus, thus reducing subsequent loads. The aerated biological filter 3, acting as a deep biological treatment unit, specializes in treating recalcitrant organic matter and decolorizing, providing high-quality feed water for the membrane system. The dual-membrane system, consisting of a polyvinylidene fluoride hollow fiber membrane in the ultrafiltration unit 4 and a polyamide composite membrane in the reverse osmosis unit 5, ensures the final effluent quality. These three components are connected in series, forming a gradient treatment mode of "biological enhancement + deep filtration + precision separation," synergistically enhancing efficiency and achieving a total COD removal rate >98%, a color removal rate >96.9%, and a desalination rate >95%.

[0032] In the aforementioned system, the aerobic granular sludge has a compact structure and is rich in microorganisms, while the biofilm in the aerated biological filter 3 grows and adheres. The combination of these two elements gives the system a strong buffering capacity against fluctuations in the quality and quantity of dyeing and printing wastewater, and strong resistance to shock loads. Experiments show that even if the influent COD is impacted to 1500 mg / L, the system can recover stable operation within 24 hours. Simultaneously, the deep pretreatment by the aerobic granular sludge reactor 2 and the aerated biological filter 3 effectively removes colloids, suspended solids, and large molecular organic matter that easily cause membrane fouling. This significantly reduces the fouling load on the polyvinylidene fluoride hollow fiber membrane and the polyamide composite membrane, extends the membrane cleaning cycle and service life, and reduces the frequency and energy consumption of chemical cleaning. Compared to the traditional "anaerobic-aerobic + dual-membrane" process, the cost per ton of water treated is reduced by more than 30%.

[0033] The system also includes a PLC automatic controller 6, which is electrically connected to the aerobic granular sludge reactor 2, the aerated biological filter 3, the ultrafiltration unit 4, and the reverse osmosis unit 5. The PLC automatic controller 6 dynamically adjusts the operating parameters of each unit based on preset programs or online monitoring data to optimize the overall system efficiency and address fluctuations in influent water quality. The PLC automatic controller 6 provides automated control of the entire process, simplifying operation and management, reducing manual intervention, and ensuring long-term stable system operation.

[0034] This invention also provides a method for the efficient treatment and resource reuse of dyeing and printing wastewater, comprising the following steps:

[0035] Step S1: The dyeing and printing wastewater enters the equalization tank 1 for homogenization and equalization.

[0036] Step S2: The effluent from the equalization tank 1 enters the aerobic granular sludge reactor 2, with an organic loading rate of 2.0~4.0 kg / (m³). 3 •d) Biological treatment is carried out under dissolved oxygen conditions of 2~4 mg / L to remove most of the organic matter and nitrogen and phosphorus pollutants;

[0037] In step S3, the effluent from the aerobic granular sludge reactor 2 enters the aerated biological filter 3 for deep treatment under conditions of hydraulic retention time of 2-4 hours and dissolved oxygen of 4-5 mg / L, further removing recalcitrant organic matter and color.

[0038] Step S4: The effluent from the aerated biological filter 3 is filtered by the ultrafiltration device 4 to remove suspended solids and colloids. The ultrafiltration membrane flux is controlled at 20~30L / (m³). 2 ·h);

[0039] In step S5, the ultrafiltration permeate enters the reverse osmosis unit 5 for desalination and fine treatment, with the operating pressure controlled at 1.0~1.5MPa, to obtain permeate that meets the reuse standards.

[0040] At the same time, the PLC automatic controller 6 monitors the operating status and water quality parameters of each unit in the system in real time, and dynamically adjusts the operating cycle of the aerobic granular sludge reactor 2, the aeration rate of the aerated biological filter 3, the backwashing frequency of the ultrafiltration device 4, and the operating pressure of the reverse osmosis device 5 to cope with fluctuations in the influent water quality and optimize the overall system efficiency.

[0041] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto. The process parameters involved in the following embodiments are preferred embodiments of the present invention, and their specific values ​​can be appropriately adjusted according to the actual influent water quality, and do not constitute a limitation on the scope of protection of the present invention.

[0042] Example 1: Treatment of High-Concentration Dyeing and Printing Wastewater

[0043] This embodiment demonstrates the effectiveness of the system in treating typical high-concentration dyeing and printing wastewater.

[0044] Raw water quality: The wastewater from a dyeing and printing factory was taken, and its quality was as follows: chemical oxygen demand (CODcr) ≈ 1200 mg / L, color ≈ 450 times, ammonia nitrogen (NH3-N) ≈ 35 mg / L, total nitrogen (TN) ≈ 55 mg / L, and conductivity ≈ 2200 μS / cm.

[0045] The system operation steps are as follows:

[0046] Step S1, Pretreatment and Homogenization: The wastewater is first passed through a mechanical screen to remove large particulate suspended solids and fibrous impurities, and then enters the equalization tank 1 for about 8 to 12 hours to equalize the water quality and quantity.

[0047] Step S2, Aerobic granular sludge treatment: The effluent from equalization tank 1 is pumped into aerobic granular sludge reactor 2 by a lift pump. This reactor adopts a sequencing batch reactor (SBR) operation mode.

[0048] Optimal operating parameters: Organic Loading Rate (OLR) controlled at 3.0 kg / (m³) 3 •d), Dissolved oxygen (DO) is controlled at 3.0 mg / L; sludge concentration (MLSS) is maintained at around 9000 mg / L; each operating cycle is 4 hours, including 0.5 h of influent, 2.5 h of aeration, 0.5 h of sedimentation, 0.5 h of drainage and short-term idle.

[0049] Treatment effect: After treatment by this unit, the COD of the effluent is reduced to about 150 mg / L, the color is reduced to about 180 times, and most of the easily degradable organic matter and some nitrogen and phosphorus are effectively removed.

[0050] Step S3, deep treatment in aerated biological filter 3: the effluent from aerobic granular sludge reactor 2 enters aerated biological filter 3.

[0051] Optimal operating parameters: The tank is filled with spherical ceramic aggregate with a filling ratio of 75%; the hydraulic retention time (HRT) is controlled at 4 hours, the dissolved oxygen (DO) is controlled at 4.5 mg / L, and continuous aeration mode is adopted.

[0052] Treatment effect: After deep biological oxidation and filtration in this unit, the COD of the effluent is further reduced to about 45 mg / L, the color is significantly reduced to about 15 times, and a large amount of recalcitrant organic matter is decomposed.

[0053] Step S4, Ultrafiltration Precision Filtration: The effluent from the aerated biological filter 3 enters the ultrafiltration system after passing through the security filter.

[0054] Optimal operating parameters: Polyvinylidene fluoride (PVDF) hollow fiber membrane is used, and the membrane flux is controlled at 25 L / (m²). 2 The operating pressure is controlled at 0.2 MPa; the system performs a 30-second backwash every 30 molecules to control membrane fouling.

[0055] Treatment effect: This unit effectively removes tiny suspended solids, colloidal substances and some bacteria from the water, ensuring the safety of the influent water for the reverse osmosis system.

[0056] Step S5, reverse osmosis desalination and purification: Ultrafiltration permeate is pumped into reverse osmosis unit 5 by a high-pressure pump.

[0057] Optimal operating parameters: Polyamide composite membrane is used, the operating pressure is controlled at 1.2MPa, the pH of the system influent is adjusted between 6.5 and 7.5 by an automatic dosing device, and the system is designed to recover 65%.

[0058] Final water quality: After treatment by this unit, the final water quality is clear, with COD < 0.6 mg / L, color < 5 times, and conductivity < 85 μS / cm, which is far superior to the standard of "Water Quality for Reclaimed Water in Textile Dyeing and Finishing Industry" (FZ / T 01107-2011). It can be directly used for production after entering the reclaimed water tank.

[0059] Operation Control and Cost: The entire system is automatically controlled by a PLC automatic controller 6 based on sensor signals such as liquid level, pressure, and dissolved oxygen, which controls the water pumps, aerators, and valves to achieve stable operation. Results from 30 consecutive days of operation show that the system has strong resistance to shock loads, the efficiency of each unit is stable, and the total cost per ton of water treated is approximately 1.85 yuan.

[0060] Example 2: Treatment of medium-concentration and high-color dyeing and printing wastewater

[0061] This embodiment demonstrates the adaptability of the system under conditions of moderate influent concentration and high color intensity.

[0062] Raw water quality: Chemical oxygen demand (CODcr) ≈ 800 mg / L, color ≈ 600 times, ammonia nitrogen (NH3-N) ≈ 25 mg / L, conductivity ≈ 1800 μS / cm.

[0063] The system operation steps are as follows:

[0064] The system flow in this embodiment is exactly the same as that in Embodiment 1, but the preferred operating parameters of some units have been optimized and adjusted according to the characteristics of the influent water quality.

[0065] (1) Aerobic granular sludge treatment: Due to the relatively low organic matter concentration, the organic loading rate (OLR) was adjusted to 2.5 kg / (m³). 3 •d) Dissolved oxygen (DO) is maintained at 2.5 mg / L to ensure treatment effectiveness while reducing energy consumption.

[0066] (2) Aerated biological filter 3 deep treatment: In view of the high color characteristics, in order to ensure sufficient biological oxidation time, the hydraulic retention time (HRT) is set to 3 hours and the dissolved oxygen (DO) is increased to 5.0 mg / L to enhance the decolorization and degradation of dyes.

[0067] (3) Ultrafiltration precision filtration and reverse osmosis desalination and purification: The operating parameters are basically the same as those in Example 1.

[0068] Treatment effect: Although the influent color is higher, the final product water color is stabilized at <3 times, COD <0.5mg / L, and conductivity <80μS / cm after enhanced decolorization by the aerated biological filter 3, which also meets the reuse requirements.

[0069] Based on the above embodiments, it is demonstrated that the system and method of the present invention not only have good treatment effect, but also have good adaptability and stability to dyeing and printing wastewater of different water qualities through the flexible parameter adjustment of the PLC system, fully demonstrating the superiority of the integrated system.

[0070] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. An integrated system for efficient treatment and resource reuse of dyeing and printing wastewater, characterized in that, The system includes an equalization tank (1) connected by pipes along the wastewater flow direction, an aerobic granular sludge reactor (2), an aerated biological filter (3), an ultrafiltration device (4), and a reverse osmosis device (5). The equalization tank (1) is used to equalize the water quality and quantity of the dyeing and printing wastewater. The aerobic granular sludge reactor (2) is used to perform biodegradation and nitrogen and phosphorus removal treatment on the effluent from the equalization tank (1). The aerated biological filter (3) is used to perform deep biological treatment and filtration on the effluent from the aerobic granular sludge reactor (2). The ultrafiltration device... (4) is used for physical screening and removal of colloidal substances from the effluent of the aerated biological filter (3). The reverse osmosis device (5) is used for desalination and deep purification of the ultrafiltration permeate, and its permeate is connected to the recycled water tank. It also includes a PLC automatic controller (6) electrically connected to the aerobic granular sludge reactor (2), the aerated biological filter (3), the ultrafiltration device (4) and the reverse osmosis device (5). The PLC automatic controller (6) is used to dynamically adjust the operating parameters of each unit of the system to optimize the overall system efficiency and cope with fluctuations in the influent water quality.

2. The integrated system for efficient treatment and resource recovery of dyeing and printing wastewater according to claim 1, characterized in that, The aerobic granular sludge reactor (2) is a sequencing batch reactor.

3. The integrated system for efficient treatment and resource recovery of dyeing and printing wastewater according to claim 1, characterized in that, The aerated biological filter (3) is filled with granular biological packing material and uses continuous aeration.

4. The integrated system for efficient treatment and resource recovery of dyeing and printing wastewater according to claim 1, characterized in that, The ultrafiltration device (4) uses a polyvinylidene fluoride hollow fiber membrane and is subjected to periodic backwashing.

5. The integrated system for efficient treatment and resource recovery of dyeing and printing wastewater according to claim 1, characterized in that, The reverse osmosis device (5) uses a polyamide composite membrane.

6. A method using the integrated system for efficient treatment and resource recovery of dyeing and printing wastewater as described in any one of claims 1-5, characterized in that, Includes the following steps: Step S1: The dyeing and printing wastewater enters the equalization tank (1) for homogenization and equalization. Step S2: The effluent from the equalization tank (1) enters the aerobic granular sludge reactor (2) for biological treatment to remove most of the organic matter and nitrogen and phosphorus pollutants; Step S3: The effluent from the aerobic granular sludge reactor (2) enters the aerated biological filter (3) for deep treatment to remove recalcitrant organic matter and color. Step S4: The effluent from the aerated biological filter (3) is filtered by an ultrafiltration device (4) to remove suspended solids and colloids; In step S5, the ultrafiltration permeate enters the reverse osmosis unit (5) for desalination and fine treatment to obtain permeate that meets the reuse standards.

7. The method for efficient treatment and resource recycling of dyeing and printing wastewater according to claim 6, characterized in that, The PLC automatic controller (6) monitors the operating status and water quality parameters of each unit in the system in real time, and dynamically adjusts the operating cycle of the aerobic granular sludge reactor (2), the aeration rate of the aerated biological filter (3), the backwashing frequency of the ultrafiltration device (4), and the operating pressure of the reverse osmosis device (5).

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